En español | After Bev Hollis got divorced four years ago, she made an unpleasant discovery: She didn't have enough money to cover her retirement.

Because her ex got the bulk of their investable assets, Hollis, 54, a veterinarian and pet photographer, found it hard to get the attention of the financial-planning firm the couple had used when they were married.

That company made its money through fees and commissions, and Hollis' account wasn't large enough to generate much income for the adviser.

"I felt like a smaller and smaller fish," recalls Hollis, who lives in Frederick, Md. "I needed someone to help me understand what was doable and what wasn't."

Hollis found that service at LearnVest, one of a new breed of digital financial firms that rely heavily on sophisticated technology — namely powerful computers and algorithms — to assess clients' financial situations and recommend investments. The idea is to let computers do what computers do best: analyze vast amounts of information and offer advice based on logic, rather than turn to brokers who may be trying to sell a particular product.

"An algorithm is reliable," says Jon Stein, founder and chief executive of one of these sites, Betterment. "It doesn't wake up on the wrong side of the bed, it doesn't have conflicts of interest, and it doesn't react to current events."

For a lot of people, good guidance doesn't have to come with a high price tag, says Michael Kitces, a partner at Pinnacle Advisory Group in Columbia, Md. Sites that simply review a portfolio, monitor it and make suggestions typically charge a flat fee depending on the amount invested, usually around just $20 a month. Those that go a step further and manage money, such as Betterment or Wealthfront, assess a charge of about 0.25 percent of the amount the client has invested with them. They generally provide a narrower range of services than comprehensive financial planners, though the pricing compares very favorably with what many advisers charge, which is typically $150 or more per hour or a fee equaling 1 percent of investments.

AARP Member Discounts

"Many of the new online financial tools represent a tremendous leap from what's been available for the past decade," says Kitces, who has studied online experts and blogs about their potential to change the shape of financial advice. Bob Veres, publisher of the San Diego–based Inside Information newsletter and website for financial advisers, sees the sites as a threat to those who aren't adding much value. Still, he doesn't think "robo-advisers" can replace the knowledge and personalized care a living, breathing financial planner provides.

"A lot of the calculation work that advisers do now can be automated," says Veres, "but the personalized advice that comes from it cannot."

There may be other drawbacks: The companies themselves are start-ups, and it's difficult to assess what their long-term performance will be. And not all start-ups survive. In fact, two digital wealth-management ventures backed by big companies — NestWise, a subsidiary of broker LPL Financial Holdings, and BloombergBlack, an investment advisory arm of the data and media giant Bloomberg LP — were shut down abruptly last year. While investors generally won't lose money managed by sites that close (because customer accounts are insured for up to $500,000 against bankruptcy and fraud), switching advisers is always disruptive.

Hollis used LearnVest to track all her financial accounts, construct a budget and connect with a certified financial planner who could answer questions about how much to save and where to invest. She filled out a detailed questionnaire and got back a 20-page plan with recommendations to increase her savings rate and keep her long-term care insurance. In follow-up phone calls, the two tackled other parts of her financial life — including her decision to sell her condo and rent for a while to free up more cash to invest. Hollis feels confident she'll be able to retire at 65 with 70 percent of her current income. "I'm in way better shape than I'd ever thought I'd be," she says.

While each company targets a slightly different audience, the sweet spot is the "mass affluent" — the 40 million or so U.S. households with assets between $100,000 and $1 million. It's a market many bigger, traditional financial-services companies are trying to reach: Vanguard Group, well known for its low-cost funds, gives free financial advice to investors with more than $500,000, and Schwab offers a financial plan to its clients for $2,000 (AARP members get a 20 percent discount). The new sites may also appeal to people with less than $100,000 to invest, since signing up is easy and often doesn't require switching accounts and big upfront costs.